A more detailed analysis of the duodenal ILC compartment demonstrated CD117(−)CRTH2(−)ILC1s and CD117( + )CRTH2(−)ILC3s to represent the major duodenal ILC subsets, whereas CRTH2(+)ILC2s were barely detectable in the duodenal mucosa of both FAP patients and non-FAP controls (Fig. 1d, e and Supplementary Fig. 1b). This evidence concerns the gene PTGDR2 and Familial adenomatous polyposis.